Well, my understanding of Patreon was not deep. After some review, I do believe that sserobinsse is correct, as in: Patreon is a place for people to sell things.
However, to say that these are transactions is not correct, but neither are donations. The answer is that it depends. The main point is that Patreon is just the hub for people to trade money for "service". And it can actually be used by people seeking donations to fund a project, donations to charity, or to sell services.
Whether it's a legally enforceable transaction depends on whether you're paying a business, organization, or an individual. An individual has no legal obligation to complete the transaction without a contract. It is just an informal agreement between individuals, or at least that's what I assume, and most of the creators here fall under this category.
So, yes, they're right that Patreon is for selling things, but not when it comes to legal liability.
And now, I'm done derailing.